In 2003 Jeep introduced the rugged Rubicon edition Wrangler. The Rubicon received numerous upgrades in comparison with a standard Jeep Wrangler. One of these upgrades was the venerable NV241OR Roctrac Transfer Case. The Roctrac transfer case offers the strength of a full size truck transfer case while also offering an impressive 4:1 low range.
The design of the NV241OR Rocktrac is based off of the robust NP241 transfer case commonly found in full size Dodge/GM trucks. Much like the truck NP241, The Roctrac received an impressively large 4 planetary gear system and a wider chain. The Roctrac has a noticeably large front section where it houses this larger 4:1 planetary gear system. The Rocktrac has numerous ribbing reinforcements around the case exterior for added case strength. The Roctrac comes factory with a 32 splined rear output shaft equipped with a fixed yoke. The front driveshaft is located on the driver side of the vehicle and is likewise offered with a 32 spline.
As with most chain driven transfer cases, the Roctrac operates in four shift modes. The transfer case shifts in the following patterns: 2wd high, 4wd high, neutral and 4wd low. The case can be identified by the silver and red metal identification tag that is riveted to the rear section of the transfer case. The Roctrac measures 15-1/4” in overall length and weighs in at about 92 lbs. The front of the transfer case uses the standard Jeep round circular 6 bolt pattern as found on the NP231. Prior to 2012, all Roctracs received a short 23 spline input shaft and were mated to either the 42RLE, NV3550 or the NSG370 transmissions. In 2012 Jeep retired the 42RLE and replaced it with the A580 five-speed automatic. The Roctrac used behind the A580 utilized a special 26 spline male shaft for the input.
Although the full size NP241 looks similar to the Rocktrac, the internal components are different. Most internal parts including both the 4:1 planetary gears and input shafts are not interchangable between the Roctrac and a standard NP241. Advance Adapters does however offer numerous transmission to transfer case adapters for the 23 spline version of the NV241OR, As to date, we do not offer any adapters for the 26 spline version of Roctrac
The TJ Rubicon version of the RockTrac utilizes a tone wheel for the speedometer. The speedometer also commonly referred to as the “vehicle speed sensor” or “VSS” is located on the rear nose cone near the rear yoke. It operates off of a three-wire, square wave signal. It should be noted that changes in tire size or ring and pinion typically require a Jeep dealership to re-flash the computer for accurate speedometer calibration. As an alternative to “re-flashing”, numerous companies offer vehicle speed calibration controller boxes.
All TJ models have the transfer case shifter linkage mounted to the body. This set-up uses a bell crank that pivots between a transfer case mounting bracket and a body mount. When the transfer case moves during a vehicle lift, transmission swap, body lift or use of flat skid plate, the transfer also moves. Even the slightest movement can upset geometery of the transfer case shifter mounting bracket. This misalignment can cause severe binding of the transfer case shifter. Advance Adapters offers an isolation bracket that once installed removes the mounting point on the body and isolates it to the transfer case. This isolation TJ shifter bracket is sold under PN715542. A second option is to upgrade the Jeep linkage by removing the bellcrank completely. We offer a complete cable shifter for TJ Roctrac transfer case and is available under PN715543.
In 2007 Jeep introduced the JK model of the Rubicon. This version of the Roctrac does not have a VSS provision as Jeep relocated the speedometer to the axle. It also should be noted that the shifter linkage was removed from the body and a cable shifter was utilized. We have seen numerous failures on this cable system mostly as a result of plastic heim joints being used. Advance Adapters offers an upgraded cable kit under PN715596. This new heavy duty design was created for the off roader who is consistently shifting the transfer case in and out of its various ranges. The improved cable and mounting system offers both a durable and dependable system that is free of easily worn out factory JK transfer case shifting system.
Over the years we have seen good success of Roctrac even behind V8 power. The Roctrac offers significant strength and low gearing benefits over the factory NP231 found in non-Rubicon Jeeps. The strength upgrades and 4:1 low range allows for this transfer case to offer the end user better offroading abilities and dependability. Although the Roctrac is significantly better than a NP231, It is not impervious to failure. It still is a chain driven transfer case and does not offer the twin stick features like an Atlas, see PNATLAS-TJ & PNATLAS-JK.
The other option for the TJ’s and JK’s with the Roctrac and the 42RLE automatic transmission is the addition of a Rubi-Crawler. This is reduction box that provides you a 2.72:1 low ratio in 2WD and 4WD in addition to a ultra-low range of 10.88:1. The Rubi-Crawler can be installed into a Jeep in a day without any drive shaft modifications, see PNRUBI-CRAWLER